A photosensitive composition composed of an o-naphthoquinonediazide compound as a photosensitive compound and novolak-type phenol resins as a binder are industrially used as excellent photosensitive compositions for producing photosensitive lithographic printing plates and photoresists. Phenols used as the raw materials for such novolak-type phenol resins include phenol, o-cresol, m-cresol, p-cresol and xylenol. Since the foregoing phenols are monohydric phenols, the photosensitive compositions require a relatively strong alkaline developer for developing the composition. However, the development by a strong alkaline developer is accompanied by disadvantages with respect to water pollution and costs. Accordingly, photosensitive compositions which can be developed by a weak alkaline developer have been desired.
When coating a photosensitive composition on a support and using it as a photosensitive lithographic printing plate, it is required that a binder used for forming the photosensitive layer of the photosensitive composition be rich in film-forming property for enduring the application of a large number of printing. Japanese Patent Application (OPI) Nos. 101,833/'82 and 101,834/'82, (European Pat. No. 54,258), disclose photosensitive compositions using the condensation products of resorcin derivatives and aldehydes or ketones as the binder and the photosensitive compositions using the aforesaid binder can be developed by a weak-alkaline developer different from photosensitive compositions using cresol-formaldehyde resin, etc., as the binder as well as have a good film-forming property as compared to the latter composition. However, when the foregoing photosensitive composition is coated on an anodically oxidized aluminum support and the plate thus produced is rubbed with a sponge, etc., impregnated with a developer for the development, a part of the photosensitive composition remains on the support at non-image portions after development, which provides an undesirable appearance as well as frequently causes stains on prints when using the developed plate as a lithographic printing plate.